[NaCL SDK] Ship sys/mount.h for newlib/pnacl.

native_client_sdk/src/examples/demo/nacl_io/nacl_io_demo.c

 /* Copyright (c) 2012 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "nacl_io_demo.h"
 
 #include <assert.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/mount.h>
 #include <pthread.h>
 
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/c/pp_module.h"
 #include "ppapi/c/ppb.h"
 #include "ppapi/c/ppb_instance.h"
 #include "ppapi/c/ppb_messaging.h"
 #include "ppapi/c/ppb_var.h"
 #include "ppapi/c/ppp.h"
 #include "ppapi/c/ppp_instance.h"
@@ skipping 334 matching lines @@
   } else if (strcmp(interface_name, PPP_MESSAGING_INTERFACE) == 0) {
     static PPP_Messaging messaging_interface = {
       &Messaging_HandleMessage,
     };
     return &messaging_interface;
   }
   return NULL;
 }
 
 PP_EXPORT void PPP_ShutdownModule() {}